Tadalafil and Blood Pressure Medicines: What Is Safe and What Is Not

Tadalafil lowers blood pressure. That is not a side effect that occasionally happens. It is part of how the medicine works, and it is why interaction questions matter more here than with most treatments.

For most people whose high blood pressure is treated and controlled, the drop is small and causes no problems. For a smaller group it is dangerous, and for one group of medicines the combination is not a risk to weigh but an absolute no.

Tadalafil relaxes smooth muscle in blood vessel walls, which increases blood flow to the erectile tissue. That same effect on blood vessels elsewhere produces a mild, usually temporary fall in blood pressure. The fall is generally small, but it becomes important when tadalafil is combined with certain medicines, or taken by people with particular heart conditions.

Key things to know

• Tadalafil is contraindicated with any form of organic nitrate. This is absolute, not a caution to be managed
• It is also contraindicated with nicorandil and with guanylate cyclase stimulators such as riociguat. Both are less well known than nitrates, and both carry the same severity
• In healthy volunteers, tadalafil produced a mean maximal fall of 1.6/0.8 mmHg lying down and 0.2/4.6 mmHg standing. Small on average, which is exactly why the exceptions matter
• Most blood pressure treatments are compatible. With the exception of alpha blockers, the extra fall is generally minor and unlikely to be clinically relevant
• Very low blood pressure and uncontrolled high blood pressure are both contraindications
• Treatment suitability depends on an individual clinical assessment

How Much Does Tadalafil Lower Blood Pressure?

It does lower blood pressure, and the measured effect in healthy volunteers is small.

UK product information records a mean maximal fall of 1.6/0.8 mmHg in blood pressure lying down, and 0.2/4.6 mmHg standing.

That average does not predict exactly what will happen in someone taking other medicines, or with underlying heart disease.

Why an Average Understates the Risk

An average is a poor guide to an individual, and three things widen the gap between the published figure and the real risk.

The figures come from healthy volunteers. Someone already on two or three blood pressure medicines, or dehydrated, or with problems in the nerves that regulate blood pressure, is not that population.

The standing figure is larger. The standing diastolic fall is bigger than the lying one. Blood pressure medicines and PDE5 inhibitors both interfere with the reflex that holds pressure up when you stand, which is why symptoms cluster around getting out of a chair or out of bed.

The risk comes from combinations. The danger is almost never tadalafil alone. It is tadalafil plus something else, and with certain medicines the effects do not simply add, they compound.

Tadalafil's long action matters here too. It can remain active for up to 36 hours after a single dose, so anything that affects blood pressure during that period overlaps with it.

People with severe heart failure or unstable angina should not take tadalafil, because of the cardiovascular demands of sexual activity.

The Contraindicated Combinations

Organic Nitrates

UK product information states that tadalafil is contraindicated in anyone using any form of organic nitrate.

Nitrates are used mainly for angina. They include glyceryl trinitrate, often shortened to GTN, as a spray, tablet or patch, along with isosorbide mononitrate and isosorbide dinitrate. The spray is the one most often overlooked, because people think of it as something they use occasionally rather than a medicine they take.

Nitrates and tadalafil work through the same nitric oxide pathway. Nitrates supply nitric oxide, and tadalafil stops the resulting signal being broken down. Together the blood-pressure-lowering effect is amplified rather than added, and the result can be a collapse in blood pressure rather than a dip.

Nicorandil

Nicorandil is licensed for preventing and treating chronic stable angina. It is often missed in this conversation because people do not think of it as a nitrate.

They should. UK product information for nicorandil states that combining it with PDE5 inhibitors, including sildenafil, tadalafil and vardenafil, is contraindicated because of the risk of severe low blood pressure.

Nicorandil works in two ways: it opens potassium channels to widen arteries, and it has a nitrate component that relaxes veins. That nitrate component is what PDE5 inhibitors amplify. Anyone taking nicorandil should treat tadalafil as ruled out.

Riociguat and Other Guanylate Cyclase Stimulators

UK product information states that combining PDE5 inhibitors, including tadalafil, with guanylate cyclase stimulators such as riociguat is contraindicated.

These medicines are used for certain forms of high blood pressure in the lungs. They act on the next step of the same signalling pathway, so the combination pushes the same system from two directions at once. It is a small group of patients, but the rule is absolute.

Informally Sold Nitrites

Amyl nitrite and related compounds, sold under informal names, are nitric oxide donors. They fall under the same contraindication, and because they are not obtained on prescription, nobody has checked the combination.

Because they may be used recreationally and do not appear on a conventional medicines list, people may forget to mention them at assessment. Mention them anyway.

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Blood Pressure Medicines That Are Usually Compatible

Most people being treated for high blood pressure can be assessed for tadalafil. UK product information states that alongside antihypertensive medicines, tadalafil may cause a blood pressure fall which, with the exception of alpha blockers, is generally minor and unlikely to be clinically relevant.

That sentence carries a lot of weight, so read what it does and does not say. It does not say the combination is risk-free. It says the effect is usually small enough not to matter clinically, and it names one exception. Suitability is still a prescriber's decision.

ACE Inhibitors, Such as Ramipril

ACE inhibitors are among the most commonly prescribed blood pressure treatments in the UK. Their names usually end in "pril".

There is no contraindication with tadalafil. Both can lower blood pressure, so a further fall is possible, particularly when treatment has recently been started or changed.

A recently started or increased ACE inhibitor is a different situation from a stable, long-standing one. And a cough or dizziness that began before tadalafil was ever considered belongs in the conversation with the prescriber.

Angiotensin receptor blockers, whose names usually end in "sartan", sit in the same position.

Calcium Channel Blockers, Such as Amlodipine

Calcium channel blockers such as amlodipine relax blood vessels directly.

There is no contraindication with tadalafil. This class already causes ankle swelling, flushing and headache in some people, and tadalafil can cause headache and flushing too.

The overlap does not make the combination unsafe, but it does mean a headache after a tablet may have two contributors, which is worth knowing before assuming tadalafil is the problem.

Beta Blockers, Such as Bisoprolol

Beta blockers slow the heart and reduce its workload. Their names usually end in "olol".

There is no general contraindication, but the prescriber should consider your heart condition and full medication list.

Anyone taking a beta blocker for angina rather than blood pressure should make sure the prescriber knows, because angina raises separate questions and often involves a nitrate as well.

Diuretics

Diuretics reduce the volume of fluid in circulation, and are frequently combined with the classes above.

There is no contraindication with tadalafil. The relevant point is that anything reducing fluid volume makes a blood pressure fall easier to provoke, particularly in hot weather, after an illness with vomiting or diarrhoea, or when you have not been drinking much.

That is a dehydration issue rather than an interaction, and it is manageable once known.

Alpha Blockers: The Exception That Matters

Alpha blockers are the one class UK product information singles out, and the detail differs between medicines in the group. That matters because they are common, and because they are prescribed for two quite different reasons.

Doxazosin

UK product information states that combining doxazosin and tadalafil increases the blood-pressure-lowering effect, and that the combination is not recommended.

That is stronger than a caution and weaker than the absolute contraindications above. In practice a prescriber will usually look for another route rather than manage the combination.

Doxazosin is used both for high blood pressure and for prostate symptoms, so it can appear on a medicines list for either reason. Always declare it at assessment.

Tamsulosin and Alfuzosin

UK product information records that the effects seen with doxazosin were not reported with alfuzosin or tamsulosin, but advises caution when using tadalafil with any alpha blocker.

So these two sit differently. They are not in the "not recommended" category, but they are not in the "no concerns" category either.

Tamsulosin in particular is very widely prescribed for prostate symptoms, and many men taking it also ask about erectile treatment, so this combination comes up often. It needs a prescriber who knows both medicines are in play.

How the Classes Compare

Usually compatible is not the same as approved for you. It means the class does not rule treatment out, and the decision still rests on your full picture.

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Blood Pressure Readings That Rule Treatment Out

Two blood pressure situations are contraindications in their own right, whatever medicines you take.

Very low blood pressure rules tadalafil out, and the low reading itself needs looking into.

Uncontrolled high blood pressure is also a contraindication. This surprises people, who assume high pressure would offset a medicine that lowers it. It does not work that way. Uncontrolled hypertension signals a cardiovascular system that has not been stabilised.

Treated and controlled high blood pressure is a different situation entirely, and is not a barrier to assessment.

Recognising Low Blood Pressure After a Tablet

Symptoms occur when blood pressure falls enough to reduce blood flow to the brain and other tissues.

What It Feels Like

• Light-headedness or dizziness, most often on standing up
• A brief greying or narrowing of vision when you stand
• Feeling weak, unsteady or unusually tired
• Nausea
• Clammy or cool skin
• A sense that you need to sit down quickly

In UK product information, dizziness is listed as an uncommon side effect of tadalafil rather than a common one. Headache is the common one.

What to Do in the Moment

1. Sit or lie down straight away. Do not try to walk it off, because a faint while standing risks injury from the fall rather than from the blood pressure itself
2. If lying down, raise your legs
3. Drink some water if you can drink normally and have no medical reason to restrict fluids, in case dehydration is contributing. Get up slowly afterwards, in stages
4. Do not take another tablet to compensate. It does not correct anything, and it increases the risk
5. Report what happened before any further treatment, so it can be assessed rather than repeated

Do You Need a Blood Pressure Check Before Starting?

You need your blood pressure to be known and reasonably current. That is not the same as a reading taken in the room five minutes beforehand.

A recent, reliable reading can form part of the assessment. If yours is unknown, the prescriber may ask you to get one first. Given that two blood pressure situations are contraindications, that gap needs closing before treatment rather than after.

What a Proper Assessment Covers

• Every medicine you take, prescription and otherwise, including anything used only occasionally, such as a GTN spray
• Recent blood pressure readings, and whether blood pressure treatment is stable
• Cardiovascular history, including angina, heart attack, stroke or heart failure
• Symptoms suggesting something undiagnosed, since erectile difficulty is often an early vascular signal
• Kidney and liver conditions, since both organs clear the medicine and reduced function means it lingers
• Eye conditions, including any previous episode of sudden vision loss in one eye

What Makes a Fall More Likely

Interactions are only part of the picture. Several ordinary situations make low blood pressure easier to provoke, and most are avoidable once you know about them.

Alcohol is the main one. UK product information records dizziness on standing and a drop in blood pressure in some people at higher alcohol doses. Alcohol and tadalafil both lower blood pressure, and both blunt the standing reflex.

Dehydration is the second, whether from hot weather, illness, exercise or simply not drinking enough. Heat can also widen blood vessels and add to light-headedness in someone already prone to low blood pressure.

What the Evidence Does Not Settle

Reporting the gaps honestly matters more than filling them.

• The published blood pressure figures come from healthy volunteers. There is no single published figure for someone taking three blood pressure medicines, because the answer depends on which three
• Product information for tamsulosin and alfuzosin records that the doxazosin effects were not reported with them. That is an absence of a reported finding, which is weaker than evidence of no effect, and it is why caution is still advised
• No published UK figure exists for how often symptomatic low blood pressure occurs in real-world use alongside blood pressure treatment, because the data is not collected that way
• Nothing here predicts an individual response. Results vary between individuals

Getting the Assessment Right

If you take blood pressure medicine and want to know where you stand, the route is a proper assessment rather than a guess from a list.

Bring the medicine names, not just what they are for. Include anything occasional, particularly a GTN spray, anything from another prescriber, and recent blood pressure readings if you have them.

Tadalafil is available as tablets taken as needed or as daily tablets, and the full range of licensed erectile dysfunction treatments shows how the options differ in onset and duration.

EveryDayMeds is registered with the General Pharmaceutical Council, number 9012878. Medicines are supplied only after clinical assessment, dispensed by a registered pharmacy, and sent in plain unbranded packaging.

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